Cooperative effect from cation and anion of pyridine-containing anion-based ionic liquids for catalysing CO2 transformation at ambient conditions

Pyridine-containing anion-based ionic liquids (PA-ILs) with two kinds of interaction sites to bind CO2, e.g., [P4444][2-OP], were found to be highly efficient for catalysing the cycloaddition reactions of atmospheric CO2 with epoxides at room temperature under metal- and halogen-free conditions, producing a series of cyclic carbonates in high yields. It was demonstrated that the cooperative interaction from two interaction sites in the anions of PA-ILs activated CO2, while the cation activated the epoxides substrates via coordination to the central P+ unit, thus resulting in the high activity of the IL catalysts.